GoImport doesn't import commented packages

[DevAlone]

What did you do? (required. The issue will be closed when not provided.)

import (
    "errors"
    // "fmt"
)

:GoImport fmt

What did you expect to happen?

import (
    "errors"
    "fmt"
)

What happened instead?

"fmt" already being imported

Configuration (MUST fill this out):

• Vim version (first two lines from :version):

NVIM v0.2.2
Build type: RelWithDebInfo

• Go version (go version):

go version go1.10 linux/amd64

• Go environment (go env):

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/user/go"
GORACE=""
GOROOT="/opt/golang"
GOTMPDIR=""
GOTOOLDIR="/opt/golang/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build027896217=/tmp/go-build -gno-record-gcc-switches"

• vim-go version:

Last installed by vim-plug

• vimrc you used to reproduce (use a minimal vimrc with other plugins disabled; do not link to a 2,000 line vimrc):

https://gist.github.com/DevAlone/4f5ec03f17d42ce3bb730060ac1eb594

[arp242]

The entire thing is a regexp-based mess of ugly. I rewrote the lot with #1559, just need to finish that up when I have the time!